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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Can we achieve clarity at W3C re what XSL, XSL-FO and XSLT are?
 repeating an old hobby horse of mine about the confused usage of terminology which is currently being applied in W3C documents with respect to "XSL" and its component technologies and more specifically the confusion about the "XSL namespace". A solution to the current confusing situation is offered at the end of the post. While the "XSL" (really XSL-FO) specification is still at CR there is a continuing opportunity to tidy up this terminology tangle. Edited quote from a past post follows: This post is a plea for a beginning in consistent use of the term "XSL" in W3C documents. The current CR stage of XSL-FO and the first WD of XSLT 1.1 give an opportunity to W3C to remove longstanding inconsistent usage and to introduce coherence and consistency. For those who have not yet considered the problem let me summarise the difficulty and inconsistency by the use of two "equations" which summarise two mutually contradictory positions about what "XSL" is which are taken (implicitly or explicitly) in the current versions of W3C documents. To avoid ambiguity I use the term "XSLT" to indicate XSL Transformations and the term "XSL-FO" to indicate XSL Formatting Objects. The two equations are: 1. XSL = XSLT + XSL-FO (see e.g. Abstract of XSL-FO CR) 2. XSL = XSL-FO Stated as baldly as this I expect to potentially elicit howls of protest along the linesof "Of course XSL is the summation of XSLT and XSL-FO". But the statements currently present in various W3C documents contradict this assumed clarity and consistency. Let me illustrate. .... In the XSLT 1.0 Recommendation of November 1999 it is stated in the Abstract, "XSLT is also designed to be used independently of XSL.", a statement which cannot be true if XSL = XSL-FO + XSLT (XSLT cannot be used independently of "XSL" since XSLT is _part of_ "XSL") and contradicts, for example, the Abstract of the XSL-FO CR. However the statement also contradicts the position taken earlier in the Abstract of XSLT 1.0: "In addition to XSLT, XSL includes ....". So, XSLT seems to be "included in" XSL but is also can be used "independent of" it. Something doesn't add up. What is happening is that the first part of the preceding sentence refers implicitly to equation 1. and the latter part to equation 2.Thus, in theXSLT 1.0 Recommendation (and repeated verbatim in the XSLT 1.1 WD) we have the use of both "equations". Which equation is true? Does XSL = XSL-FO + XSLT or does XSL = XSL-FO? XSLT 1.0 effectively uses these two mutually contradictory positions within a few lines of each other.The same inconsistency also appears in the current XSL-FO CR. As mentioned above, the Abstract indicates unequivocally that XSL includes both XSLT andXSL-FO. But in Section 2, confusingly labelled "Introduction to XSL Transformations" it is stated, "The XSL namespace has the URI http://www.w3.org/1999/XSL/Format.". The placement of a statement about what I would call the XSL-FO namespace in a section on XSLT is confusing enough. But if, as the Abstract of the CR implicitly states, XSL = XSL-FO + XSLT then there are two "XSL" namespaces viz. http:www.w3.org/1999/XSL/Format AND http://www.w3.org/XSL/Transform, not one as the XSL-FO CR states. There are many ways of slicing up these inconsistencies but, in my view, they are founded in the use of "XSL" in the same documents to have two distinct meanings. Is "XSL" the same as "XSL-FO + XSLT"? Or is "XSL" the same as"XSL-FO"? I would suggest that the W3C "XSL" editors ... by which I mean the editors for the XSL-FO CR and the new XSLT 1.1 WD need to decide what "XSL" is and then use the term precisely and consistently. At present neither precision nor consistency is achieved.I hope these two examples serve to illustrate the ambiguity or inconsistencyof the use of the term "XSL" in current W3C documents. I could, quite possibly, go on at length about how the inconsistency plays out in various W3C documents. Rather, I think it is more important to find a solution that is logical, clear and consistent.Suffice to say that the inconsistency within XSL/XSL-FO/XSLT specs plays out to some degree in other specs too. My suggestion for how to move toward coherence would be: 1. Confine the generic term "XSL" to situations which refer to XSLFO _and_XSLT collectively. 2. When referring to XSL Formatting Objects the abbreviation to be usedshould be either "XSL-FO" or "XSLFO". 3. When referring to XSL Transformations the abbreviation used should be"XSL-T" or "XSLT". 4. It should be recognised that there are two "XSL Namespaces". The XSLT Namespace has a namespace URI of http://www.w3.org/1999/XSL/Transform. The XSL-FO Namespace has a namespace URI of http://www.w3.org/1999/XSL/Format. 5. The confusing "indicative prefix" (my term) for those two namespacesshould be corrected/made consistent. I would suggest that the XSLT namespace use the "indicative prefix" of "xslt" rather than "xsl" i.e. as an example, the present<xsl:stylesheet> element would become <xslt:stylesheet>. Similarly the "fo"indicative prefix would become "xslfo" i.e. <fo:root> would become< xslfo:root>. I would propose that the W3C Core XML Group (do I have the terminology correct?) review the current inconsistency in terminology across W3C specs currently in draft or under revision and give clear, unambiguous guidance on which meaning "XSL" has in W3C documents.<side_issue> <side_issue> With regard to the more specific problem relating to the naming of the current XSL-FO CR could that not be called the "Extensible Stylesheet Language Formatting Objects, XSL-FO" Recommendation in due time? And could another very short "XSL" REC indicate that XSL version 1.0 subsumes the XSLT REC of November 1999 and the XSL-FO REC, currently at CR stage? Then whenXSLT 1.1 is finalised "XSL 1.1" could be defined as "XSL-FO 1.0" plus "XSLT1.1"? Just a thought. :) The recent Requirements documents for XSLT 2.0, XPath 2.0 indicate such an approach with respect to, for example, XQuery 1.0.< /side_issue> Consistent usage of the term "XSL" is desirable. With the current fluidity of an XSL-FO CR and an XSLT 1.1 WD there is an early opportunity for W3C to introduce consistency where hitherto inconsistent and confusing usage of theterm "XSL" has been rather too visible. *** Re-edited quote ends *** Surely it is wiser to tidy this now rather than impose this confusion in perpetuity? Andrew Watt 
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